Color image forming apparatus and image output method

ABSTRACT

A color image forming apparatus and an image output method capable of producing a PDL output without interfering with the execution of a calibration procedure is provided. A main controller rasterizes PDL data from a network on a DRAM as image data. The main controller determines whether or not a calibration procedure is being executed. If it is determined that the calibration procedure is being executed, a production of a PDL image output is put in a queue until the calibration procedure is completed. If it is determined that the calibration procedure is not being executed, the image data on the DRAM is transferred to a printer portion at an appropriate timing so that the printer portion may produce a printed page of the image data.

[0001] This application claims priority from Japanese Patent ApplicationNo. 2002-237476 filed Aug. 16, 2002, which is incorporated hereinto byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a color image forming apparatusand an image output method connected to a network.

[0004] 2. Description of the Related Art

[0005] With the recent trend in more and more copying machines goingdigital, multifunctional machines equipped with a plurality of functionshave been put into practical applications, including such applicationsas using a scanner or printer of a copying machine for transmitting andreceiving data through facsimile and printing page image byreconstructing it from PDL (Page Description Language) data availablefrom a computer or the like. Such a multifunctional machine is arrangedso as to be able to operate even among a plurality of functions, suchas, for example, transmitting PDL-converted image through facsimile, inaddition to a single function of a copying function, a facsimilefunction, a PDL printing function, or the like. In addition, themultifunctional machine may also be configured so as to allow, whenconnected to an individual apparatus such as a computer or the like overa LAN, the computer or the like to use the functions provided by themultifunction machine.

[0006] In such multifunctional machines, a common control program for aprinter portion is shared among the copying machine function and the PDLprint function or facsimile function or the like. Or, a common controlprogram for a reader is shared among the copying machine function andthe facsimile function or a scanner function or the like. This approachallows the capacity required for the control programs for realizing thevarious functions to be reduced, thus achieving the required functionseconomically and in a simplified manner.

[0007] Further, by providing such a multifunctional machine with alarge-capacity hard disk capable of storing image data, it is possibleto store and control data representing an image scanned by the scanner,an image reconstructed through PDL, a document received by facsimile, orthe like as an image file or a document file in the hard disk.

[0008] In a printing unit of a color printer in an image formingapparatus, on the other hand, it is known that variations in outputcharacteristics and unit-to-unit variations as a result of thesevariations in output characteristics occur, which makes it difficult toachieve an output image of a uniform quality. It is known, for example,that printed images of different tones of color result each time aprinting process is carried out even using the same original.

[0009] This is attributable to the following fact in a printing unitemploying, for example, an electrophotographic method. Specifically, insuch an electrophotographic process as laser exposure, formation of anelectrostatic latent image on a photoconductive element, development oftoner, toner image transfer to a paper medium, or fusing of the tonerimage onto the paper medium by heat, there occurs a change in an ambienttemperature or humidity surrounding the apparatus, or a change in any ofcomponent parts of the apparatus with time, which eventually results inthe amount of toner fused on the paper medium being varied. It is knownthat such instability in printing output characteristics is not uniqueonly to the electrophotographic method, but the phenomenon occurslikewise in an ink jet method, a thermal transfer method, and othervarious methods.

[0010] Calibration processing is then carried out. In the calibrationprocessing, an image of a predetermined test gradation pattern isproduced, an image density of the pattern produced is measured, andprinting characteristics of the printing unit are then corrected basedon the results of the measurement of the image density.

[0011] An image forming apparatus itself is, however, used for producinga printed output of the test gradation pattern or processing measurementdata of the image density of the test gradation pattern, even if animage data is transferred or a print command is issued thereto while theprinting unit is being calibrated. This makes it impossible for theprinting unit to execute the particular printing function. That is, acomputer or the like requests a PDL print function, a facsimilefunction, or the like to be executed through a network, regardless ofwhether the calibration process is being carried out or not in the imageforming apparatus. This results in a print command being rejected, or aprocess for generating image forming data, such as rasterization of PDLdata, being initiated after the completion of calibration. As a result,printing processing is retarded.

[0012] It is therefore a first object of the present invention toprovide a color image forming apparatus and an image output methodcapable of producing a PDL output without interfering with the executionof a calibration process, when the execution of a PDL print function isrequested over a network during execution of the calibration process.

[0013] It is a second object of the present invention to provide a colorimage forming apparatus and an image output method capable of producingan output of a facsimile-received document without interfering with theexecution of a calibration process, when the execution of a facsimilereception and print function is requested over a network duringexecution of the calibration process.

SUMMARY OF THE INVENTION

[0014] To achieve the foregoing objects, an image forming apparatusaccording to the present invention creates image forming data based onimage data received from a host device and forms an image based on theimage forming data. The image forming apparatus according to the presentinvention is provided with calibration means for executing a calibrationprocess, through which image output characteristics of the image formingapparatus are set to predetermined ones, and control means for at leastallowing the image forming data to be created, if the calibration meansis in the calibration process when image data is received from the hostdevice.

[0015] The image forming apparatus according to the present invention isconnected to the host device over a network. The image forming apparatusis further provided with rasterization means for reconstructing imagedata from PDL data received over the network, storage means for storingimage data reconstructed by the rasterization means, and image formingmeans for forming an image based on the image data stored in the storagemeans. The control means is provided with discrimination means fordetermining whether or not a calibration process is being executed whenimage data is stored in the storage means. If the discrimination meansdetermines that a calibration process is being executed, the controlmeans puts the image forming means in a standby state. After theexecution of the calibration process is completed, the control meansallows the image forming means to start forming an image. If thediscrimination means determines that a calibration process is not beingexecuted, the control means lets the image forming means to startforming the image.

[0016] Further, the image forming means is capable of forming an imagethrough an electrophotographic method.

[0017] The image forming means is also capable of forming an imagethrough an ink jet method.

[0018] An image forming apparatus according to another aspect of thepresent invention creates image forming data based on fax-received datareceived from a host device and forms an image based on the imageforming data. The image forming apparatus according to the preferredembodiment of the present invention is provided with calibration meansfor executing a calibration process, through which image outputcharacteristics of the image forming apparatus are set to predeterminedones, and control means for at least allowing the image forming data tobe generated, if the calibration means is in the calibration processwhen fax-received data is received from the host device.

[0019] The image forming apparatus according to the present invention isconnected to the host device over a network. The image forming apparatusis further provided with interpretation means for interpretingfax-received data received over the network, storage means for storingimage data interpreted by the interpretation means, and image formingmeans for forming an image based on the image data stored in the storagemeans. The control means is provided with discrimination means fordetermining whether or not a calibration process is being executed whenimage data is stored in the storage means. If the discrimination meansdetermines that a calibration process is being executed, the controlmeans puts the image forming means in a standby state. After theexecution of the calibration process is completed, the control meansallows the image forming means to start forming an image. If thediscrimination means determines that a calibration process is not beingexecuted, the control means lets the image forming means to startforming the image.

[0020] Further, the image forming means is capable of forming an imagethrough the electrophotographic method and also through the ink jetmethod.

[0021] An image forming method according to further aspect of thepresent invention creates image forming data based on image datareceived from a host device and forms an image based on the imageforming data. The image forming method according to the preferredembodiment of the present invention is provided with a calibration stepfor executing a calibration process, through which image outputcharacteristics of the image forming apparatus are set to predeterminedones, and a control step for at least allowing the image forming data tobe created, if the calibration means is in the calibration process whenimage data is received from the host device.

[0022] The image forming apparatus according to the present invention isconnected to the host device over a network. The image forming apparatusis provided with rasterization means for reconstructing image data fromPDL data received over the network, storage means for storing image datareconstructed by the rasterization means, and image forming means forforming an image based on the image data stored in the storage means.The control step is provided with a discrimination step for determiningwhether or not a calibration process is being executed when image datais stored in the storage means. If the discrimination step determinesthat a calibration process is being executed, the control step puts theimage forming means in a standby state. After the execution of thecalibration process is completed, the control step allows the imageforming means to start forming an image. If the discrimination stepdetermines that a calibration process is not being executed, the controlstep lets the image forming means to start forming the image.

[0023] An image forming method according to further aspect of thepresent invention generates image forming data based on fax-receiveddata received from a host device and forms an image based on the imageforming data. The image forming method according to the preferredembodiment of the present invention is provided with a calibration stepfor executing a calibration process, through which image outputcharacteristics of the image forming apparatus are set to predeterminedones, and a control step for at least allowing the image forming data tobe generated, if the calibration means is in the calibration processwhen fax-received data is received from the host device.

[0024] The image forming apparatus according to the present invention isconnected to the host device over a network. The image forming apparatusis provided with interpretation means for interpreting fax-received datareceived over the network, storage means for storing image datainterpreted by the interpretation means, and image forming means forforming an image based on the image data stored in the storage means.The control step is provided with discrimination means for determiningwhether or not a calibration process is being executed when image datais stored in the storage means. If the discrimination means determinesthat a calibration process is being executed, the control step puts theimage forming means in a standby state. After the execution of thecalibration process is completed, the control step allows the imageforming means to start forming an image. If the discrimination meansdetermines that a calibration process is not being executed, the controlstep lets the image forming means to start forming the image.

[0025] The above and other objects, effects, features and advantages ofthe present invention will become more apparent from the followingdescription of embodiments thereof taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026]FIG. 1 is a block diagram showing one preferred embodiment of thepresent invention;

[0027]FIG. 2 is a sectional view showing the construction of a reader200 and a printer portion 300 shown in FIG. 1;

[0028]FIG. 3 is a block diagram showing the construction of a readerimage forming portion 222 shown in FIG. 2;

[0029]FIG. 4 is a block diagram showing the construction of a controller110 shown in FIG. 1;

[0030]FIG. 5 is a block diagram showing the construction of a portionresponsible for forming an image in a scanner I/F 140 shown in FIG. 4;

[0031]FIG. 6 is a block diagram showing the construction of a portionresponsible for forming an image in a printer I/F 145 shown in FIG. 4;

[0032]FIG. 7 is a block diagram showing the construction of a graphicprocessor 135 shown in FIG. 4;

[0033]FIG. 8 is an explanatory diagram explaining an operation of animage zooming portion 802 shown in FIG. 7;

[0034]FIG. 9 is an explanatory diagram explaining an operation of animage zooming portion 802 shown in FIG. 7;

[0035]FIG. 10 is a flowchart showing a typical copy image outputprocedure;

[0036]FIG. 11 is a flowchart showing a typical calibration procedure;

[0037]FIG. 12 is a diagram showing a typical gradation pattern; and

[0038]FIG. 13 is a flowchart showing a typical PDL image outputprocedure.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0039] Preferred embodiments according to the present invention will bedescribed in detail with reference to the accompanying drawings.

[0040]FIG. 1 is a block diagram showing one preferred embodiment of thepresent invention. The block diagram shown in FIG. 1 represents anexample of an image input/output system. A reader 200 optically reads anoriginal image and converts it to corresponding image data. The reader200 is composed of a scanner unit 210 having a function of reading anoriginal and an original take-up and feed unit 250 having a function oftransporting pages of an original document.

[0041] A printer portion 300 transports recording paper, prints imagedata thereon as a visible image, and feeds the printed recording paperout of the apparatus. The printer portion 300 is composed of a papertake-up unit 360 having a plurality of types of recording papercassettes, a marking unit 310 having a function of transferring andfusing the image data onto the recording paper, and a paper exit unit370 having a function of sorting or stapling and feeding out of theapparatus the printed recording paper.

[0042] A controller 110 is electrically connected to the reader 200 andthe printer portion 300 and further connected via a network 400 to hostcomputers 401, 402.

[0043] The controller 110 provides a copying function by controlling thereader 200 so as to read the image data on the original and controllingthe printer portion 300 so as to output the image data on the recordingpaper. The controller 110 also provides a scanner function thattranslates the image data read by the reader 200 to corresponding codeddata and transmits the coded data via the network 400 to the hostcomputer, and a printer function that converts the coded data receivedfrom the host computer via the network 400 to corresponding image dataand outputs the image data to the printer portion 300.

[0044] An operation panel 150, connected to the controller 110, isprovided with a liquid crystal touch panel for providing a user I/F foran operation of the image input/output system.

[0045]FIG. 2 is a sectional view showing the construction of the reader200 and the printer portion 300 shown in FIG. 1. The original take-upand feed unit 250 of the reader 200 takes up and feeds each page of theoriginal document, one page at a time in ascending order of page, onto aplaten glass 211. When a reading operation of the original page iscompleted, the original take-up and feed unit 250 feeds the originalpage on the platen glass 211 out, of f the platen glass 211. When theoriginal page is transported onto the platen glass 211, a lamp 212 isturned ON and an optics unit 213 is moved for carrying out an exposurescanning process for the original page. Light reflected off the originalpage is guided at this time by mirrors 214, 215, 216 and a lens 217 tostrike a CCD image sensor (hereinafter referred to as the “CCD”) 218.The CCD 218 reads the image of the original page as the original page isscanned in the manner described above. A reader image forming portion222 performs predetermined processing for the image data output from theCCD 218 and outputs results thereof to the controller 110 by way of ascanner I/F 140. A printer image forming portion 352 outputs an imagesignal transmitted from the controller 110 by way of a printer I/F 145to a laser driver 317.

[0046] The laser driver 317 of the printer portion 300 drives laserlight generator 313 to 316 to emit a laser light beam in accordance withthe image data output from the printer image forming portion 352.Photoconductive drums 325 to 328 are irradiated with the laser lightbeam by mirrors 340 to 351, and a latent image is formed on thephotoconductive drums 325 to 328 in accordance with the laser lightbeam. Developing units 321 to 324 develop a latent image with toner ofblack (Bk), yellow (Y), cyan (C), and magenta (M), respectively. Thedeveloped images of toner of different colors are transferred to thepaper for producing a full-color printed paper.

[0047] A paper cassette 360, 361, or a manual bypass tray 362 takes upand feeds a sheet of paper at a timing in synchronism with the start ofirradiation of the laser light beam. The paper moves past a registrationroller 333 and is then attracted onto a surface of a transfer belt 334and transported. The toner images sticking to the photoconductive drums325 to 328 are transferred onto the recording paper. The recordingpaper, on which the toner images are placed, is transported to a fuser335 which fuses the toner images in the recording paper through heat andpressure. The recording paper, which has moved past the fuser 335, isfed out of the apparatus by an exit roller 336. An exit unit 370 tidiesup sheets of recording paper fed out to sort or staple together intosets or stacks of printed paper.

[0048] If a setting is made for two-sided recording, the recording papertransported up to the exit roller 336 is fed backward by changing thedirection of rotation of the exit roller 336 backward. A flapper 337then guides the recording paper toward a duplex transport path 338. Therecording paper guided to the duplex transport path 338 is next taken upand fed to the transfer belt 334 at the timing as described in theforegoing.

[0049] <Description of the Reader Image Forming Portion 222>

[0050]FIG. 3 is a block diagram showing the construction of the readerimage forming portion 222 shown in FIG. 2. In the reader image formingportion 222, the original placed on the platen glass 211 is read andresultant data thereof is converted to a corresponding electrical signalby the CCD 218. In the case of a color sensor, the CCD 218 may be atype, in which an R color filter, a G color filter, and a B color filterare mounted in-line in order of R, G, and B on a 1-line CCD. Or, the CCD218 may still be a type that is a 3-line CCD, each line being mountedwith an R filter, a G filter, and a B filter, respectively. The filtermay also be an on-chip type, or separated from the CCD. The electricalsignal (an analog image signal) is then applied to the image formingportion 222 and sampled and held (S/H) by a clamp, amplifier, S/H, andA/D 501. With a dark level of the analog image signal clamped to areference voltage, the analog image signal is then amplified to arequired level (order of processing is not limited to that described)and goes through A/D conversion. The analog image signal is convertedto, for example, a digital signal with each of R, G, and B being 8 bits.The RGB signal then undergoes a shading correction and a blackcorrection at a shading portion 502 before being output to thecontroller 110.

[0051] <Description of the Controller 110>

[0052]FIG. 4 is a block diagram showing the construction of thecontroller 110 shown in FIG. 1. A main controller 111 is composed mainlyof a CPU 112, a bus controller 113, and various types of I/F controllercircuits.

[0053] The CPU 112 and the bus controller 113 control the operation ofan entire controller 110. The CPU 112 runs based on a program read byway of a ROM I/F 115 from a ROM 114. Operations of interpreting PDL(Page Description Language) coded data received from the host computerand converting the coded data to equivalent raster image data are alsodescribed in this program and processed through software functions. Thebus controller 113 controls data transfer carried out across differentI/Fs, controlling reconciliation of bus contention and DMA datatransfer.

[0054] A DRAM 116 is connected to the main controller 111 through a DRAMI/F 117, used as a work area for the CPU 112 to operate and an area forstoring image data.

[0055] A CODEC 118 compresses raster image data stored on the DRAM 116through a format of MH, MR, MMR, JBIG, JPEG, or the like anduncompresses compressed and stored coded data to raster image data. AnSRAM 119 is used as a temporary work area for the CODEC 118. The CODEC118 is connected to the main controller 111 by way of an I/F 120 anddata transfer with the DRAM 116 is carried out through DMA as controlledby the bus controller 113.

[0056] A graphic processor 135 performs processing of image rotation,image zooming, color space conversion, and binarization for the rasterimage data stored on the DRAM 116. An SRAM 136 is used as a temporarywork area for the graphic processor 135. The graphic processor 135 isconnected to the main controller 111 by way of an I/F 137 and datatransfer with the DRAM 116 is carried out through DMA as controlled bythe bus controller 113.

[0057] A network controller 121 is connected to the main controller 111through an I/F 123, and to an external network through a connector 122.A common network is Ethernet (a registered trademark). An expansionconnector 124 for connecting an expansion board and an I/O controler 126are connected to a general-purpose high-speed bus 125. A host computer Ibus is commonly available as the general-purpose high-speed bus. The I/Ocontroler 126 is provided with an asynchronous serial communicationscontroller 127 in two channels for transmitting a control command to,and receiving it from, each CPU of the reader 200 and the printerportion 300. The asynchronous serial communications controller 127 isconnected to a scanner I/F 140 and a printer I/F 145 through an I/O bus128.

[0058] A panel I/F 132, connected to an LCD controller 131, is composedof an I/F for displaying data on a liquid crystal screen on theoperation panel 150 and a key input I/F 130 for inputting a hard key ora touch panel key. The operation panel 150 is provided with the liquidcrystal display, a touch panel input device affixed to the liquidcrystal display, and a plurality of hard keys. A signal input throughthe touch panel or a hard key is transmitted to the CPU 112 by way ofthe panel I/F 132, while the liquid crystal display displays image datatransmitted from the panel I/F 132. Functions as they relate tooperations of this printing apparatus, image data, and the like aredisplayed on the liquid crystal display. A real-time clock module 133 isfor updating and storing a date and a time-of-day controlled within theapparatus, backed up by a backup battery 134.

[0059] An E-IDE interface 161 is for connecting an external storagedevice. In the apparatus according to the embodiment of the presentinvention, a hard disk drive 160 is connected through this interface forstoring image data in a hard disk 162 and loading image data from thehard disk 162. Connectors 142, 147 are connected, respectively, to thereader 200 and the printer portion 300. The connectors 142, 147 arecomposed of asynchronous serial I/Fs 143, 148 and video I/Fs 144, 149.

[0060] The scanner I/F 140 is connected to the reader 200 through theconnector 142, and connected to the main controller 111 through ascanner bus 141. The scanner I/F 140 is provided with a function forperforming predefined processing for an image received from the reader200. The scanner I/F 140 is also provided with a function for outputtinga control signal generated based on a video control signal transmittedfrom the reader 200 to the scanner bus 141. The bus controller 113controls data transfer from the scanner bus 141 to the DRAM 116.

[0061] The printer I/F 145 is connected to the printer portion 300through the connector 147, and connected to the main controller 111through the printer bus 146. The printer I/F 145 is therefore providedwith a function for performing predefined processing for image dataoutput from the main controller 111 and outputting resultant datathereof to the printer portion 300. In addition, the printer I/F 145 isalso provided with a function for outputting a control signal generatedbased on a video control signal transmitted from the printer portion 300to the printer bus 146. The bus controller 113 controls transfer ofraster image data converted on the DRAM 116 to the printer portion 300.The raster image data is transferred through DMA to the printer portion300 by way of the printer bus 146 and the video I/F 149.

[0062] <Description of the Image Forming Portion of the Scanner I/F 40>

[0063]FIG. 5 is a block diagram showing the construction of a portionresponsible for forming an image in the scanner I/F 140 shown in FIG. 4.If the CCD 218 is a 3-line CCD, linking processing is performed asfollows because of different scanning positions involved among differentlines. Specifically, a linking/MTF corrector 601 adjusts the amount ofdelay for each line in accordance with a scanning speed for the imagesignal transmitted via the connector 142. That is, the linking/MTFcorrector 601 corrects a signal timing to ensure that the scanningposition is the same for all three lines. In addition, since a scanningMTF varies depending on the scanning speed, these variations are furthercorrected by means of an MTF correction. An input masking portion 602corrects a digital signal, the scanning position timing of which hasbeen corrected, in accordance with spectral characteristics of the CCD218 and spectral characteristics of the lamp 212 and the mirrors 214 to216. An output from the input masking portion 602 is sent to an ACScounter 603 and the main controller 111.

[0064] <Description of the Image Forming Portion of the Printer I/F 145>

[0065]FIG. 6 is a block diagram showing the construction of a portionresponsible for forming an image in the printer I/F 145 shown in FIG. 4.An image signal transmitted from the main controller 111 via the printerbus 146 is first applied to a LOG converter 701. The LOG converter 701translates an RGB signal to a corresponding CMY signal through LOGconversion. Next, a moiré remover 702 removes moiré. A UCR/maskingportion 703 subjects the CMY signal, which has been processed for moiréremoval, to UCR processing to generate a CMYK signal. The maskingportion of the UCR/masking portion 703 then corrects the CMYK signal toa type suitable for printer output. The signal processed by theUCR/masking portion 703 is applied to a y corrector 704. The γ corrector704 is provided with a correction table for making density adjustmentsfor each of C, M, Y, and K. The γ corrector 704 uses this correctiontable to make the necessary density adjustments. A filter 705 thenperforms smoothing and edge processing. Image data goes through thesetypes of processing before being sent to the printer portion 300 via theconnector 147.

[0066] <Description of the Graphic Processor 135>

[0067]FIG. 7 is a block diagram showing the construction of the graphicprocessor 135 shown in FIG. 4. The graphic processor 135 is providedwith modules for performing, respectively, image rotation, imagezooming, color space conversion, and binarization. The SRAM 136 is usedas a temporary work area for each of the modules provided for thegraphic processor 135. The specific work area of the SRAM 136 isstatically assigned for each module in advance to prevent contentionamong different modules for a single work area. The graphic processor135 is connected to the main controller 111 through the I/F 137 and datatransfer with the DRAM 116 is carried out through DMA as controlled bythe bus controller 113.

[0068] The bus controller 113 controls setting of a mode or the like foreach of the modules provided for the graphic processor 135 and timingfor transfer of image data to each module.

[0069] <Description of an Image Rotator 801>

[0070] Processing operations performed by an image rotator 801 will beexplained. The CPU 112 makes settings for image rotation control in thebus controller 113 through the I/F 137. The bus controller 113, on theother hand, uses these settings made by the CPU 112 through the I/F 137to make settings required for image rotation in the image rotator 801.These settings may include specifically, for example, an image size, adirection of rotation, an angle of rotation, and the like. When thesenecessary settings have been made, the CPU 112 once again gives the buscontroller 113 a permit to transfer image data. In accordance with thispermit, the bus controller 113 begins a transfer of image data from theDRAM 116 or a device connected through the corresponding I/F. For thepurpose of this specification, the image size subject to image rotationis 32 pixels x 32 lines, and an image transfer is carried out in unitsof 24 bytes (8 bits each of R, G, and B for one pixel) when transferringimage data over an image bus.

[0071] As described in the foregoing, to acquire an image of 32 pixels x32 lines, it is necessary to carry out the data transfer in theaforementioned units 32×32 times, and to transfer image data from adiscontinuous address (see FIG. 8).

[0072] To ensure that an image rotated through a desired angle can beobtained upon reading, the image data transferred through discontinuousaddressing is temporarily written in the SRAM 136. If the image is to berotated through, for example, 90 degrees counterclockwise, the imagedata to be transferred is written in a Y-axis direction as shown in FIG.9. When reading, the image data is read in an X-axis direction, whichresults in the original image to be rotated.

[0073] After image rotation for 32 pixels×32 lines (writing of data inthe SRAM 136) has been completed, the image rotator 801 read the imagedata from the SRAM 136 through the reading method mentioned in theforegoing and transfers the image to the bus controller 113.

[0074] After having received the image data that has undergone rotationprocessing, the bus controller 113 transfers data to the DRAM 116 or thecorresponding device on the I/F through continuous addressing.

[0075] A series of these processing operations is repeated until aprocessing request is no longer received from the CPU 112 (or, untilprocessing for the required number of pages is completed).

[0076] <Description of an Image Zooming Portion 802>

[0077] Processing operations performed by an image zooming portion 802will be explained. The CPU 112 makes settings for image zooming controlin the bus controller 113 through the I/F 137. The bus controller 113uses these settings made by the CPU 112 through the I/F 137 to makesettings required for image zooming (a zoom ratio in a main scanningdirection, a zoom ratio in a sub-scanning direction, an image size afterzooming, and the like) in the image zooming portion 802. When thesenecessary settings have been made, the CPU 112 once again gives the buscontroller 113 a permit to transfer image data. In accordance with thispermit, the bus controller 113 begins a transfer of image data from theDRAM 116 or a device connected through the corresponding I/F.

[0078] The image zooming portion 802 temporarily stores the image datareceived from the bus controller 113 in the SRAM 136. Using the SRAM 136as an input buffer, the image zooming portion 802 performs interpolationprocessing for the data stored for the required number of pixels and/orthe required number of lines in accordance with the zoom ratio in themain scanning direction and/or in the sub-scanning direction, therebyenlarging or reducing the image as necessary. The data, after havingbeen subjected to the zooming, is rewritten in the SRAM 136 and the SRAM136 is then used as an output buffer. Next, the image zooming portion802 reads the image data from the SRAM 136 and transfers it to the buscontroller 113.

[0079] Having received the image data that has been subjected tozooming, the bus controller 113 transfers the data to the DRAM 116 orthe corresponding device on the I/F.

[0080] <Description of a Color Space Converter 803>

[0081] Processing operations performed by a color space converter 803will be explained. The CPU 112 makes settings for color space conversioncontrol in the bus controller 113 through the I/F 137. The buscontroller 113 uses these settings made by the CPU 112 through the I/F137 to make settings required for color space conversion control (acoefficient for matrix calculation, table values of an LUT (look-uptable) 804, and the like to be described later) in a color spaceconverter 803 and the LUT 804. When these necessary settings have beenmade, the CPU 112 once again gives the bus controller 113 a permit totransfer image data. In accordance with this permit, the bus controller113 begins a transfer of image data from the DRAM 116 or a deviceconnected through the corresponding I/F.

[0082] The color space converter 803 performs a 3-by-3 matrixcalculation represented by the following equation for each pixel of theimage data received. $\begin{pmatrix}X \\Y \\Z\end{pmatrix} = {{\begin{pmatrix}{a11} & {a12} & {a13} \\{a21} & {a22} & {a23} \\{a31} & {a32} & {a33}\end{pmatrix}\begin{pmatrix}{R + {b1}} \\{G + {b2}} \\{B + {b3}}\end{pmatrix}} + \begin{pmatrix}{c1} \\{c2} \\{c3}\end{pmatrix}}$

[0083] In the above equation, R, G, and B are inputs; X, Y, and Z areoutputs; and a11, a12, a13, a21, a22, a23, a31, a32, a33, b1, b2, b3,c1, c2, and c3 are coefficients.

[0084] Color space conversion of various types can be performed throughcalculations performed using the aforementioned equation, including, forexample, a conversion from an RGB color space to a Yuv color space.

[0085] A conversion by means of the LUT 804 is next performed for thedata after the matrix calculation. This permits even a nonlinearconversion. It goes without saying that it is possible not to performthe LUT conversion substantially by setting a table outputting values ofdata as are without involving any conversion of the data.

[0086] The color space converter 803 thereafter transfers image datathat has undergone the color space conversion processing to the buscontroller 113.

[0087] Having received the image data that has been subjected to thecolor space conversion processing, the bus controller 113 transfers thedata to the DRAM 116 or the corresponding device on the I/F.

[0088] <Description of an Image Binarization Portion 805>

[0089] Processing operations performed by an image binarization portion805 will be explained. The CPU 112 makes settings for binarizationcontrol in the bus controller 113 through the I/F 137. The buscontroller 113 uses these settings made by the CPU 112 through the I/F137 to make settings required for binarization processing (various typesof parameters in accordance with an applicable conversion method, andthe like) in the image binarization portion 805. When these necessarysettings have been made, the CPU 112 once again gives the bus controller113 a permit to transfer image data. In accordance with this permit, thebus controller 113 begins a transfer of image data from the DRAM 116 ora device connected through the corresponding I/F.

[0090] The image binarization portion 805 performs the binarizationprocessing for the image data received. As a method for binarization,the image data is binarized through a simple comparison made with apredetermined threshold value. It goes without saying that the imagedata can be binarized by a dither method, an error diffusion method, animproved error diffusion method, or the like.

[0091] The image binarization portion 805 thereafter transfers imagedata that has undergone the binarization processing to the buscontroller 113.

[0092] Having received the image data that has been subjected to thebinarization processing, the bus controller 113 transfers the data tothe DRAM 116 or the corresponding device on the I/F.

[0093] <Sequence for Outputting a Copy Image>

[0094]FIG. 10 is a flowchart showing a typical copy image outputprocedure. Instep S4001, a user makes copy settings for a correspondingcopy image output job on the operation panel 150. The copy settingsinclude the number of copy sets or stacks to be produced, a paper size,one-sided/two-sided, an enlargement/reduction ratio, sort output,stapling, and the like.

[0095] In step S4002, when a copy start command is issued on theoperation panel 150, the main controller 111 of the controller 110controls the reader 200 through the scanner I/F 140 and the connector142 to scan the image data on the original. First of all, the originaltake-up and feed unit 250 takes up and feeds each page of the originaldocument, one page at a time, placed therein onto the platen glass 211and, at the same time, detects the size of the original page. Based onthe size of the original page, the original page is exposed to light andscanned so that the image data thereon can be read. The image data readis stored on the DRAM 116. In the conventional copying machine, zoomingprocessing in the sub-scanning direction is accomplished by varying atraveling speed of the optics unit 213 in accordance with the settingmade of the enlargement/reduction ratio among other copy settings notedin the foregoing, that is a zoom ratio in the sub-scanning direction. Inthe preferred embodiment according to the present invention, however,the image data is invariably scanned at a full size (100%), regardlessof the setting made of the enlargement/reduction ratio among other copysettings noted in the foregoing, and the zooming processing is done bythe graphic processor 135 to be described later both for the mainscanning direction and the sub-scanning direction.

[0096] In step S4003, the graphic processor 135 performs an imageforming process based on the copy setting parameters described in theforegoing. For example, if an enlargement of 400% is set, the modulespecifically responsible for image zooming provided in the graphicprocessor 135 is used to perform the zooming processing both for themain scanning direction and the sub-scanning direction. When the imageforming process for the image data is completed, the operation proceedsto step S4005.

[0097] In step S4005, the graphic processor 135 transfers the image dataafter the image forming process to the main controller 111. The maincontroller 111 stores the image data transferred from the graphicprocessor 135 on the DRAM 116.

[0098] In step S4006, the main controller 111 transfers the image datastored on the DRAM 116 to the printer portion 300 at an appropriatetiming, while controlling the printer portion 300 through the printerI/F 145 and the connector 147.

[0099] In step S4007, the controller 110 controls the printer portion300 to produce a printed page of the image data. When the transfer ofthe image data is completed, namely when the corresponding copy job iscompleted, a production of a printed page is completed.

[0100] <Sequence for Calibration>

[0101]FIG. 11 is a flowchart showing a typical calibration procedure. Instep S1001, a calibration command is issued on the operation panel 150.The start of the calibration procedure may be commanded by the user asembodied in the preferred embodiment of the present invention. It isstill possible to configure so as to automatically start the calibrationprocedure when a predetermined condition is met.

[0102] In step S1002, when a gradation pattern output command is issuedon the operation panel 150, the main controller 111 generates agradation pattern of a bit-map format 901 for the calibration procedureand stores the gradation pattern on the DRAM 116. The gradation pattern901 generated herein is a pattern of showing changes in a toner stickingarea ratio in eight steps from 0% to 100% for cyan (C), magenta (M),yellow (Y), and black (K) corresponding to the four colors of toner usedin the printer portion 300, as shown in FIG. 12. That is, patchesrepresenting a specific area ratio varying in eight different steps aregenerated as each of rows 902, 903, 904, and 905 for C, M, Y, and K,respectively.

[0103] In step S1003, the main controller 111 transfers the image dataof the gradation pattern 901 stored on the DRAM 116 to the printerportion 300 at an appropriate timing, while controlling the printerportion 300 through the printer I/F 145 and the connector 147, therebyproducing a printed page of the gradation pattern 901 on a paper medium.

[0104] In step S1004, a gradation pattern scan command is issued on theoperation panel 150.

[0105] Instep S1005, the main controller 111 of the controller 110controls the reader 200 through the scanner I/F 140 and the connector142 to scan the image data on the original.

[0106] In step 1006, luminance data of R, G, and B obtained through thescanning operation is converted to corresponding density values of C, M,Y, and K. These density values are compared with previously storedreference values for creating a correction table for each of C, M, Y,and K. The correction tables created through these steps are stored inthe γ corrector 704, which completes the calibration procedure.

[0107] It is determined that a calibration procedure is being executedwhen the apparatus is executing any of the steps described in theforegoing. It is nonetheless possible to determine that a calibrationprocedure is being executed when any specific step or a combinationthereof is executed; that is, it is not necessary that all of the stepsdescribed in the foregoing be executed to make a decision that acalibration procedure is underway.

[0108] According to the preferred embodiment of the present invention,the gradation pattern is explained using patches of eight differentsteps for each color of toner. The number of steps is not, however,limited to eight, but any will suffice. If the gradation pattern doesnot fit to a single sheet of paper, it may cover a plurality of sheetsof paper and, for each of these sheets of paper, the steps from stepS1002 through step S1005 may be repeated.

[0109] <Sequence for Producing a PDL Image Output>

[0110]FIG. 13 is a flowchart showing a typical PDL image outputprocedure. When a PDL image output is to be produced, in step S3001, theuser makes print settings for the corresponding PDL image output jobthrough a printer driver user interface on the host computer 401. Theprint settings include the number of copy sets or stacks to be produced,a paper size, one-sided/two-sided, an output page order, sort output,stapling, and the like.

[0111] In step S3002, a print command is issued on the host computer 401and driver software installed in the host computer 401 converts codeddata to be subjected to printing on the host computer 401 to what iscalled PDL data. The converted PDL data, together with print settingparameters set in step S3001, is transferred to the controller 110 overthe network 400.

[0112] In step S3003, the CPU 112 of the main controller 111 of thecontroller 110 rasterizes the PDL data transferred through the connector122 and the network controller 121 to image data based on the printsetting parameters described in the foregoing. Rasterization of theimage data is carried out on the DRAM 116. When the rasterization of theimage data is completed, the operation proceeds to step S3004.

[0113] In step S3004, the main controller 111 transfers the image dataconverted on the DRAM 116 to the graphic processor 135.

[0114] In step S3005, the graphic processor 135 forms an imageindependently of the print setting parameters described in theforegoing. If, for example, the paper take-up unit 360 of the printerportion 300 is loaded with A4R paper only, despite the setting of thepaper size made to A4 as defined with the print setting parameters, animage output that coincides with the output paper can be produced byrotating the image through 90 degrees using the graphic processor 135.When image formation of the image data is completed, the operationproceeds to step S3006.

[0115] In step S3006, the graphic processor 135 transfers the image dataafter image formation to the main controller 111. The main controller111 then stores the image data transferred from the graphic processor135 on the DRAM 116.

[0116] In step S3007, it is determined whether or not the maincontroller 111 is executing a calibration procedure. If it is determinedthat the main controller 111 is executing a calibration procedure, thePDL image output is put in a queue. If it is determined that the maincontroller 111 is not executing a calibration procedure, the operationproceeds to step S3008. The decision to be made to determine if acalibration procedure is being executed or not is made each time theimage formation for PDL data representing one page is completed if thereare involved a plurality of pages of the PDL data. A print cycle for thepages of images, for which image formation has been completed, cantherefore be started as soon as the calibration procedure is completed,even if image formation for all pages involved of the PDL data is yet tobe completed. This makes for a printing operation at a high speed. Inthis case, processing performed through the steps from step S3001 tostep S3006 for printing pages, for which image formation has beencompleted, is executed in parallel with processing performed for the PDLdata, for which image formation is yet to be completed.

[0117] In step S3008, the main controller 111 transfers the image datastored on the DRAM 116 to the printer portion 300 at an appropriatetiming, while controlling the printer portion 300 through the printerI/F 145 and the connector 147.

[0118] In step S3009, the controller 110 controls the printer portion300 to produce a printed page of the image data. When the transfer ofthe image data is completed, namely when the corresponding PDL job iscompleted, a production of a printed page is completed. Through thearrangement as described in the foregoing, since processing for PDLconversion and image formation is carried out and the formed image datais stored on the DRAM 116 even while a calibration procedure is beingexecuted, the print cycle can be started as soon as the calibrationprocedure is completed, thus realizing a high-speed printing operation.

[0119] In the preferred embodiment of the present invention as describedin the foregoing, the decision to determine if a calibration procedureis being executed or not is made during a sequence of PDL image outputand subsequent processing is carried out based on the results of thedecision made. It is nonetheless to be understood that the invention isnot limited to only this embodiment. To be more specifically, thedecision to determine if a calibration procedure is being executed ornot may be made also during a sequence of fax-received image output andthe subsequent processing may be carried based on the results of thedecision made.

[0120] According to the preferred embodiment of the present invention asconfigured as described in the foregoing, even if a PDL print job isloaded by way of the network during the execution of a calibrationprocedure, it is possible to produce the PDL output without interferingwith the execution of the calibration procedure.

[0121] Further, even if a fax-received image print job is loaded fromthe network during the execution of a calibration procedure, printing ofthe fax-received image can be made without affecting the execution ofthe calibration procedure.

[0122] The present invention has been described in detail with respectto preferred embodiments, and it will now be apparent from the foregoingto those skilled in the art that changes and modifications may be madewithout departing from the invention in its broader aspect, and it isthe intention, therefore, in the apparent claims to cover all suchchanges and modifications as fall within the true spirit of theinvention.

What is claimed is:
 1. An image forming apparatus for creating imageforming data based on image data received from a host device and formingan image based on said corresponding image forming data, comprising:calibration means for executing a calibration process for settingparticular image output characteristics for said image formingapparatus; and control means for simultaneously at least creating saidimage forming data, if said calibration means is executing thecalibration process when image data is received from said host device.2. An image forming apparatus according to claim 1, said image formingapparatus being connected to said host device over a network and furthercomprising: rasterization means for reconstructing image data from PDLdata received over said network; storage means for storing image datareconstructed by said rasterization means; and image forming means forforming an image based on the image data stored in said storage means,wherein said control means has a discrimination means for determiningwhether or not a calibration process is being executed when image datais stored in said storage means and, if said discrimination meansdetermines that a calibration process is being executed, said controlmeans puts said image forming means in a standby state and, after theexecution of said calibration process is completed, said control meansallows said image forming means to start forming an image and, if saiddiscrimination means determines that a calibration process is not beingexecuted, said control means lets said image forming means to startforming the image.
 3. An image forming apparatus according to claim 1 or2 wherein said image forming means is a color image forming apparatusfor forming an image through an electrophotographic method.
 4. An imageforming apparatus according to claim 1 or 2, wherein said image formingmeans is a color image forming apparatus for forming an image through anink jet method.
 5. An image forming apparatus for creating image formingdata based on fax-received data received from a host device and formingan image based on said corresponding image forming data, comprising:calibration means for executing a calibration process for settingparticular image output characteristics for said image formingapparatus; and control means for simultaneously at least creating saidimage forming data, if said calibration means is executing thecalibration process when fax-received data is received from said hostdevice.
 6. An image forming apparatus according to claim 5, said imageforming apparatus being connected to said host device over a network andfurther comprising: interpretation means for interpreting fax-receiveddata received over the network; storage means for storing image datainterpreted by said interpretation means; and image forming means forforming an image based on the image data stored in said storage means,wherein said control means has a discrimination means for determiningwhether or not a calibration process is being executed when image datais stored in said storage means and, if said discrimination meansdetermines that a calibration process is being executed, said controlmeans puts said image forming means in a standby state and, after theexecution of said calibration process is completed, said control meansallows said image forming means to start forming an image and, if saiddiscrimination means determines that a calibration process is not beingexecuted, said control means lets said image forming means to startforming the image.
 7. An image forming apparatus according to claim 5 or6, wherein said image forming means is an image forming apparatus forforming an image through an electrophotographic method.
 8. An imageforming apparatus according to claim 5 or 6, wherein said image formingmeans is a color image forming apparatus for forming an image through anink jet method.
 9. An image forming method for creating image formingdata based on image data received from a host device and forming animage based on said image forming data, comprising: a calibration stepfor executing a calibration process for setting particular image outputcharacteristics for said image forming apparatus; and a control step forsimultaneously at least creating said image forming data, if saidcalibration means is executing the calibration process when image datais received from said host device.
 10. An image forming method accordingto claim 9, said image forming apparatus being connected to said hostdevice over a network and further comprising: rasterization means forreconstructing image data from PDL data received over said network;storage means for storing image data reconstructed by said rasterizationmeans; and image forming means for forming an image based on the imagedata stored in said storage means, wherein said control step has adiscrimination step for determining whether or not a calibration processis being executed when image data is stored in said storage means and,if said discrimination step determines that a calibration process isbeing executed, said control step puts said image forming means in astandby state and, after the execution of said calibration process iscompleted, said control step allows said image forming means to startforming an image and, if said discrimination means determines that acalibration process is not being executed, said control step lets saidimage forming means to start forming the image.
 11. An image formingmethod for creating image forming data based on fax-received datareceived from a host device and forming an image based on said imageforming data, comprising: a calibration step for executing a calibrationprocess for setting particular image output characteristics for saidimage forming apparatus; and a control step for simultaneously at leastcreating said image forming data, if said calibration means is executingthe calibration process when fax-received data is received from saidhost device.
 12. An image forming method according to claim 11, saidimage forming apparatus being connected to said host device over anetwork and further comprising: interpretation means for interpretingfax-received data received over the network; storage means for storingimage data interpreted by said interpretation means; and image formingmeans for forming an image based on the image data stored in saidstorage means, wherein said control step has a discrimination means fordetermining whether or not a calibration process is being executed whenimage data is stored in said storage means and, if said discriminationmeans determines that a calibration process is being executed, saidcontrol step puts said image forming means in a standby state and, afterthe execution of said calibration process is completed, said controlstep allows said image forming means to start forming an image and, ifsaid discrimination means determines that a calibration process is notbeing executed, said control step lets said image forming means to startforming the image.